#include<iostream>
using namespace std;
#include<vector>
class Solution {
public:
    void rotate(vector<vector<int>>& matrix) {
        int n = matrix.size();
        for (int i = 0; i < n; ++i)
            for (int j = i + 1; j < n; ++j)
                swap(matrix[i][j], matrix[j][i]);
        for (int i = 0; i < n; ++i)
            for (int j = 0; j < n / 2; ++j)
                swap(matrix[i][j], matrix[i][n - j - 1]);
        return;
    }
};